The present invention relates to novel compounds which are 9-substituted carbacyclin analogs, to processes for the preparation of said carbacyclin analogs and the use of said analogs as pharmacological agents or as intermediates for the preparation of compounds useful as pharmacological agents. This invention also relates to chemical intermediates for preparing the novel 9-substituted carbacyclin compounds described and claimed herein.
Prostacyclin is an endogenously produced compound in mammalian species, being structurally and biosynthetically related to the prostaglandins (PG's). In particular, prostacyclin exhibits the structure and carbon atom numbering of formula I when the C-5,6 positions are unsaturated. For convenience, prostacyclin is often referred to simply as "PGI.sub.2 ". For description of prostacyclin and its structural identification, see Johnson, et al, Prostaglandins 12:915 (1976). Carbacyclin, 6a-carba-PGI.sub.2, exhibits the structure and carbon atom numbering indicated in formula II when the C-5,6 positions are unsaturated. Likewise, for convenience, carbacyclin is referred to simply as "CBA.sub.2 ".
A stable partially saturated derivative of PGI.sub.2 is PGI.sub.1 or 5,6-dihydro-PGI.sub.2 when the C-5,6 positions are saturated, depicted with carbon atom numbering in formula I when the C-5,6 positions are saturated. The corresponding 5,6-dihydro-CBA.sub.2 is CBA.sub.1, depicted in formula II when the C-5,6 positions are saturated.
A formula as drawn herein which depicts a prostacyclin-type product or an intermediate useful in the preparation thereof, represents that particular stereoisomer of the prostacyclin-type product which is of the same relative stereochemical configuration as prostacyclin obtained from mammalian tissues or the particular stereoisomer of the intermediate which is useful in preparing the above stereoisomer of the prostacyclin type product. As drawn, formula I corresponds to that of PGI.sub.2 endogenously produced in the mammalian species. In particular, refer to the stereochemical configuration at C-8 (.alpha.), C-9 (.alpha.), C-11 (.alpha.) and C-12 (.beta.) of endogenously produced prostacyclin. The mirror image of the above formula for prostacyclin represents the other enantiomer.
The term "prostacyclin analog" or "carbacyclin analog" represents that stereoisomer of a prostacyclin-type product which is of the same relative stereochemical configuration as prostacyclin obtained from mammalian tissues or a mixture comprising stereoisomer and the enantiomers thereof. In particular, where a formula is used to depict a prostacyclin type product herein, the term "prostacyclin analog" or "carbacyclin analog" refers to the compound of that formula or a mixture comprising that compound and the enantiomer thereof.